Electric furnace



Nov. 29, 1927.

J; M. wEED ELECTRIC FURNACE Filed March 25. 1926 Inventor` James M Weed.

HLS Attorney.

Patented Nov. 29, 1927.

`UNITED STATES PATENT OFFICE.

.IaMns M. WEED, or

sCoTIA, new YonK,nssIenoa To GENERAL ELECTRIC CoM- ranr, A coitieonaTIoivV or New Yoan.

i ELECTRIC URNACE.

Application filed March 23, 1926. Serial No. 961,843.

My invention relates to electric furnaces, more specifically. to electric metal melting furnaces, and has for its object the provision of a simple, reliable andv efficient electric furnace for melting metals in which provision is made for producing a circulation of the molten metal. y

Y In carrying out my invention in one form T provide an` electrically insulating partil tion in the ,melting Crucible, this partition being spaced from the bottom of the crucible, andelectrodes on opposite sides of the partition whereby an electric heating current can be passed through the metal.

For amore Complete understanding lof my invention reference should be had to the accompanying drawing inV which 1 is a sectional view showing in lsomewhat diagrammatic fashion an electric melting fur-` nace embodyinginy invention; Fig. 2 is a sectional view along the line 2.-2 of Fig. 1 looking in the direction of the arrows; while Fig. 3 is a sectional View similar to Fig. 2 but showing a modified form of myl l invention. Y

Referring to the drawing, my invention in one form embodies a Crucible 10 made of a suitable heat refractory and electrically insulating material, such as lire clay. This y Crucible may be provi-ded with an outer protecting metallic jacket 11. A spout 12 is provided to facilitate pouring of the molten metal, and the Crucible may be mounted on horizontal pivots in a well known manner to facilitate the pouring.v The Crucible 10 is arranged to provide a reservoir 13 for the molten charge which is connected at the botf tom with an elongated reservoir 14C having a transverse sectional area much less than the transverse sectional area of the reservoir 13. As shown, reservoir 14 depends vertically from the bottom of the upper reservoir 13 although it may be inclined.

The Crucible 10 is also provided with a vertical partition 15 extending centrally across the reservoirs 13 and 14. rThis partition is made of heat refractory electrically insulating material and it may be molded integrally with the Crucible. It is joined with 50 the sidewalls of the Crucible down to the lower end of the reservoir 14 at which pointa space 16 is provided between the lower end of the partition and the bottom of the Crucible. The edect of the partition is lll 55 therefOln t0 Provide a -U"Shaped duct 17 back to the other electrode'.

-current passed through thefcharge in the wliich is Connected at its ends with the boti tom of the reservoir 13. At its upper end the `partition 15 divides the reservoir 13 'into two equal portions which Vare connected respectivelyv with Vthe ends of the U-shaped duct. Electrodes 18y and 19 are provided on opposite sides of the partition whereby an electric heating current may bepassed from one electrode through the U-shaped duct The electrodes will be connectedto a suitable source of elec- 'trical supply 20, for example, through alow voltage transformer 21. t V

.In the operation of the furnace a sulficient amount of molten charge 1s provided in the crucible to ill'thev duct 17 and thus establish an electric circuit from one lelectrode to the other, whereby heat is generated by the duct 17. A brisk circulation `of` the'hotter met-al in the duct 17 is produced by electrof magnetic repulsion between the twov upright lengths or legs of the U-shaped duct. This Vwill be made clear when it is observed` that the current in the two legs is flowing in opposite directions. There will, therefore, be an electromagnetic repulsive force between them, which force, acting on the molten metal, tends to force the metal toward the outer sides of the two legs, that is, toward the sides most remote from each other. This i action results in an increased fluid pressure in the molten charge in the vicinity of these remotely situated sides, and since the metal is prevented from flowing downward by the closed bottom of the reservoir it flows upward along the remote sides of the branches, as indicated by the arrows, the cooler molten charge from the reservoir 13 flowing downward adjacentthe sides of the partition 15 to take the place of the hotter metal. By means of this circulation the charge is maintained at a substantially uniform temperature, and the heat generated within the duct is delivered to the two portions of the reservoir 13 whereby additional cold Charge fed into this reservoir will be quickly melted. In thev modified form of my invention shown in Fig. 3, the twolegs of the U-shaped duct are displaced horizontally in the direction parallel to the partition 15. This arrangement brings the two most remote portions of these legs at the ends 22 and 23 of the transverse sections,`with the result that the molten metal is forced upward in these regions, and the colder metal flows downward in the regions most closely adjacent each other, i. e., the opposite ends 24 and 25. -This provides for -ireer `circulation since the tWo oppositely flowingstreams oit molten metal in each leg are in more remotely situ ated portions ot the duct, Whereas in the form shown in Figs. 1 and 2 these streams of molten metal are more closely adjacent to each other, being in regions separated by the least transverse sectional dimension of the duct.

Vhile I have described my invention as embodied in concrete form and as operating in a specific manner in accordance with the provisions of the patent statutes, it should be understood that I do not limit my inven` tion thereto since various modifications thereof Will suggest themselves to those skilled in the art Without departing from the spirit ot my invention, the scope of Which is set forth in the annexed claims.

Vhat I claim as new and desire to secure by Letters Patent of the United States is l. An electric furnace comprising a cruciblel providing` a reservoir for the charge di- `vided into a plurality of separate portions connected together at their bottoms through a duct having contiguous legs lying in parallel planes, and means for passing an electric heating current through the portion oithe charge in said duct.

2. An electric furnace comprising a crucible providing a reservoir for the charge divided into a plurality of separate portions connected together at their bottoms through a duct having contiguous substantially parallel legs, and ymeans for passing an electric heating current through the portion of the charge in said duct.

3. An electric furnace comprising a crucible providing a reservoir for the charge divided into tvvo portions having their bottoms connected by a U-shaped duct, and electrodes in electrically conductingrelation with the molten charge in said portion whereby a heating current can be passed through the portion of the charge in the duct from one electrode to the other. f

1I. An electric metal melting furnace comprising a Crucible providing a reservoir for Vthe charge, said reservoir being provided .with a smaller elongated portion at the bottom, and an electrically insulating partition in said reservoir spaced from the bottom thereof dividing said reservoir and said smaller portion into two portions connected together at the bottom of said smaller por tion, said smaller portion thereby constituting a U-shaped duct,rand electrodes in contact with the molten metal on opposite side-s of said partition tor passing a heating current through the charge.

In Witness whereof I have hereunto set my hand this 22nd day of March, 1926.

JAMES M. WTEED. 

